An anatomical view of a human stomach S and associated features is shown in FIG. 1A. The esophagus E delivers food from the mouth to the proximal portion of the stomach S. The z-line or gastro-esophageal junction Z is the irregularly-shaped border between the thin tissue of the esophagus and the thicker tissue of the stomach wall. The gastro-esophageal junction region G is the region encompassing the distal portion of the esophagus E, the z-line, and the proximal portion of the stomach S.
Stomach S includes a fundus F at its proximal end and an antrum A at its distal end. Antrum A feeds into the pylorus P which attaches to the duodenum D, the proximal region of the small intestine. Within the pylorus P is a sphincter that prevents backflow of food from the duodenum D into the stomach. The middle region of the small intestine, positioned distally of the duodenum D, is the jejunum J.
FIG. 1B illustrates the tissue layers forming the stomach wall. The outermost layer is the serosal layer or “serosa” S and the innermost layer, lining the stomach interior, is the mucosal layer or “mucosa” MUC. The submucosa SM and the multi-layer muscularis M lie between the mucosa and the serosa.
Various types of implants are positionable within the esophagus or stomach. These include prosthetic valves implanted for treatment of gastro-esophageal reflux disease. Another category of stomach implants includes prosthetic implants for controlling obesity. These include space-occupying devices such as inflatable balloons tethered to the stomach interior. Other obesity-controlling implants are shown and described in U.S. application Ser. No. 09/940,110, filed Aug. 27, 2001 and U.S. application Ser. No. 10/118,211006 filed Apr. 8, 2002, and U.S. Provisional Application No. 60/379,306 filed May 10, 2002, U.S. application Ser. Nos. 10/345,666 and 10/345,1104 filed Jan. 16, 2003. These applications are owned by the assignee of the present application, and the disclosures of these applications are incorporated herein by reference. Certain forms of these devices involve positioning a restrictive device in the proximal stomach. For example, a prosthetic pouch 2 of the type shown in FIG. 2A may be positioned in the proximal stomach or at the gastro-esophageal junction region as shown in FIG. 2B. The pouch may act as a restrictor, limiting the amount of food intake by restricting passage of food from the esophagus into the stomach.
This type of pouch 2 may include a proximal opening 4 and a smaller distal opening 6 and forms a small reservoir that collects masticated food from the esophagus—thereby limiting the amount of food that can be consumed at one time. Because of its small volume (which may be on the order of approximately 2 cc-300 cc in volume, but is preferably in the range of 10-30 cc), the pouch functions to limit the amount of food that can be consumed at one time. Over time the food within this reservoir descends into the stomach through the distal opening.
As the pouch fills with food, it may distend, imparting pressure against the upper stomach and lower esophageal sphincter causing the patient to experience sensations of fullness. Other types of restrictive devices are disclosed in the above-identified prior applications as well as in this application.
The pouch 2 or other restrictive implant may be formed of a flexible material. Examples of such materials include, but are not limited to polyesters (e.g. Dacron® polyester), ePTFE fabric (e.g. GoreTex® fabric or others), a polyurethane such as ChronoFlex® polyurethane, nylon fabrics, silicone, other polymeric materials, and bioabsorbable materials (e.g. PLLA, PGA, PCL, poly-anhydride etc). In the case of the pouch 2, it is optimal but not mandatory that the material prevents passage of food through the sides of the pouch. The material may be a composite of compliant, semi-compliant and/or non-compliant materials that give different regions of the pouch different degrees of compliance so as to allow/limit expansion of the pouch in various locations. For example, it may be desirable to provide a pouch with a fairly elastic exit port to as to prevent occlusion in the event a large piece of food is ingested and/or to control the exit pressure of food from the pouch, whereas the proximal end of the pouch may be stiffer to prevent bulging. Varying degrees of compliance may also be built into the pouch by varying the cross-sectional thickness in different regions of the pouch. The material may be coated with a lubricious, bio-compatible, chemically inert material, such as paraleyne, to reduce friction on the base material's surface which will help prevent sticking and food build up on the device.
The restrictive implant may be reinforced with, constructed of, or supported by supporting members, such as a soft mesh, a cage structure, ribs, rings etc. The supporting members may be formed of stainless steel, polymer, shape memory materials such as nitinol, shape memory alloys, or shape memory polymers, or thickened regions of material. The implant may be constructed so as to be self-expanding, so that it will spring radially open into an expanded condition upon ejection from a deployment device or catheter.
The pouch 2 or other implant in the stomach/esophagus may be fixed in place using sutures 8a, 8b or other means such as clips or suitable adhesives at anchor points around the perimeter of the proximal opening 4. The implant may include a reinforced section such as rim section 9 on pouch 2 for receiving the sutures 8a, 8b or other anchoring means. As illustrated in FIG. 2B, where anchoring means such as clips or sutures are used, the anchoring means may be passed completely through the wall of the stomach as with suture 8a (called a “full thickness” suture or clip), or partially through the wall of the stomach as with suture 8b (called a “partial thickness” suture or clip). One suture attachment device found useful for applying sutures between the pouch and tissue is the “Sew-Right” suturing device available from LSI Solutions of Victor, N.Y. Although the pouch may be secured to the esophageal tissue, it is more preferable to apply sutures/clips below the Z-line to allow for attachment to the thicker tissue of the stomach wall.
Once secured within the stomach, the implant and associated anchoring means are subjected to significant forces caused by stomach motility and by forces imparted against the pouch by ingested food. Such forces may be imparted against restrictive devices such as pouch 2 as well as other forms of gastro-esophageal implants, such as prosthetic valves implanted within the esophagus for treatment of gastro-esophageal reflux disease or space-occupying implants for hunger control. Over time, such forces could cause the implant to become detached from the wall of the stomach or esophagus due to erosion of the stomach/esophageal tissue at the anchoring points. It is thus desirable to provide an anchoring mechanism that will retain an implant within the stomach and/or esophagus over an extended period of time.